Tree harvester

ABSTRACT

A tree harvester for felling, limbing and cross-cutting tree trunks, comprising a limbing head (15) and felling head (16) assembly which is carried by a boom system. The limbing head (15) and the felling head (16) are detachably connectable to one another and are commonly pivotal about a point (21) on the boom system in conjunction with a tree felling operation. The limbing head (15) and the felling head (16) can be moved away from one another along the boom system (10, 18) in conjunction with a tree-trunk limbing and cross-cutting operation, and also in different directions away from the location on the boom system at which they are commonly pivotal.

FIELD OF THE INVENTION

The present invention relates to a tree harvester, forest processor, forfelling, limbing and cross-cutting tree trunks, comprising an assemblywhich includes a tree-limbing head and a tree-felling head and which iscarried by a boom system, wherein the limbing head and the felling headcan be detachably connected together and are commonly foldable about apoint on the boom system in a tree-felling mode.

BACKGROUND OF THE INVENTION

A tree harvester of this kind is known, for instance, from SwedishPatent Specification 8600948-7 publication number 463 067). The limbinghead and the felling head of this earlier known tree harvester can beconnected detachably to one another and the assembly is mounted as aunit for pivotal movement about a pivot point at one end of an armsystem to a tree-felling position in which the limbing head and thefelling head are able to commonly grip the tree to be felled. The armsystem includes at least one fixed first boom and a second boom whichcan be moved longitudinally in relation to the fixed boom, e.g.telescoped, wherein the limbing head is attached to the further boom andthe felling head is attached to the fixed, first boom. The limbing headand the felling head are mutually separated when the second boom isextended out from the first boom, and the tree is limbed by moving thelimbing head away from the felling head with the trunk of the tree heldfirmly by the gripping claws of the felling head. The axially movablesecond boom is moved in the longitudinal direction of the first boomwith the aid of pivot arms.

One drawback with the aforesaid known arrangement is that very longbooms and pivot arms are required in order to obtain an acceptablelength of movement between the limbing head and the felling head inconjunction with a tree limbing and cross-cutting operation.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a treeharvester which affords more effective movement between the limbing headand the felling head.

This object is achieved with an inventive tree harvester that has thefeatures set forth in the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be now be described in more detail with reference toa non-limiting embodiment thereof and also with reference to theaccompanying drawings, in which

FIG. 1 is a schematic side view of the boom system of an inventive treeharvester and shows a boom-carried tree-felling assembly in an upwardlydrawn position;

FIG. 2 is a view similar to the view of FIG. 1 but shows the fellingassembly extended to a tree-felling position; and

FIG. 3 illustrates the boom system of the inventive tree harvester withthe boom system extended, and also shows other components and detailswith the boom system suspended from a schematically indicated crane arm.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is thus a side view of an inventive boom system and shows thefixed boom 10 on which there is mounted an attachment 11 to which aso-called tower structure 12 having a rotator 13 is attached, saidrotator being supported by a crane arm 14 attached to a forest tractornot shown. The tower structure, rotator and crane arm are shown in FIG.3, but not in FIG. 1. One end of the fixed boom 10 carries the fellingassembly, which is comprised of a limbing head 15 and a felling head 16.Although FIG. 1 shows the limbing head 15 connected with the fellinghead 16, it will be understood that these two parts of the assembly canbe separated from one another as shown in FIG. 3. The fixed boom 10 hasthe form of a box-profile of essentially rectangular cross-section.

The limbing head 15 typically includes a pair of trunk gripping clawswhich can be positioned slightly away from the trunk when moving thelimbing head axially along the tree, so that the tree can be limbed bymoving the limbing head along the trunk. The limbing head has a lockingpin 17 intended for insertion into a corresponding opening in thefelling head, so as to enable the two heads to be connected together toform a unit.

The felling head 16 is also of conventional design and in addition totrunk-gripping claws also includes a saw, for instance a chain saw, withwhich the trunk of a tree can be cross-cut, both when felling the treeand when cutting the trunk into given lengths.

The limbing head 15 is not actually carried on the fixed boom 10, but onan outwardly extendable boom 18 of slightly narrower dimensions than thefixed boom 10, as shown in FIG. 3, this slightly narrower boom 18 beinghoused within the fixed boom and capable of being fully retractedtherein, as shown in FIG. 1. The extendable boom also has a generallybox-like, rectangular cross-sectional profile. The felling head 16 iscarried on the fixed boom 10 by means of a traveller 19, which will bedescribed below with reference to FIG. 3. In the position shown in FIG.1, the felling head 16 is securely held with the aid of a tilt cylinder20, for instance a hydraulic piston-cylinder device which is mountedbetween the felling head 16 and the traveller 19 and to which hydraulicpressure can be supplied either to hold the piston in the position shownin FIG. 1 or to extend the piston to the position shown in FIG. 2. Thetraveller 19 has a generally U-shape and is carried on the fixed boom 10by means of slide blocks (not shown), which enable the traveller to bemoved in the longitudinal direction of the fixed boom.

As beforementioned, FIG. 2 shows the felling assembly extended to atree-felling position, i.e. the position taken by the assembly inrelation to the boom system when a tree is to be felled. As shown infigure, the piston of the tilt cylinder 20 is extended at this stage,and the whole of the felling assembly is therewith swung about a pivotpoint 21 by means of which the limbing head 15 is supported at theoutermost end of the extendable boom 18. Thus, the limbing head 15 andthe entire felling assembly are pivotal about the pivot pin 21 and canbe swung from the position shown in FIG. 1 to the position shown in FIG.2.

The limbing head 15 is preferably provided with locking means (notshown) which lock the limbing head 15 in its upwardly lifted position(FIGS. 1 and 3) at the extendable boom when the limbing head is notconnected to the felling head. This locking means may have the formdescribed in the aforesaid Swedish Patent Specification SE 8600948-7.

As mentioned above, FIG. 3 shows the boom system in the position inwhich the extendable boom 18 is fully extended from the fixed boom 10,and in which the limbing head 15 and the felling head 16 are spaced at amaximum from one another. As indicated at 22, the extendable boom 18 isprojected from the fixed boom 10 with the aid of a boom-projectingpiston-cylinder device 22 which is housed in the fixed boom 10 and whichis attached at one end to a pin 23 in the extendable boom and at theother end to a pin 24 in the rear end of the fixed boom 10. Theboom-extending piston-cylinder device 22 is conveniently a hydraulicdevice to which hydraulic fluid is delivered through a delivery conduitnot shown. The limbing head 15 is attached to the outer end of theextendable boom 18 by means of the pin 21 and therewith accompanies theextendable boom as it is extended out of the fixed boom 10.

To enable the traveller 19, and therewith also the felling head 16, tobe moved along the fixed boom 10, the traveller is connected to theextendable boom 18 by means of chains, an upper chain 25 and a lowerchain 26, such that the traveller 19 will move at the same speed andthrough the same distance as that moved by the extendable boom along thefixed boom 10, but in the opposite direction. To this end, the upperchain 25 is attached to an upper part of the traveller 19 and extends,via an upper guide wheel 27, to an attachment (not shown) mounted on theextendable boom 18. The lower chain 26 is connected to the rear lowerpart of the traveller and extends over a guide wheel 28 located at therearmost end of the fixed boom (to the right in FIG. 2) and returns inthrough the interior of the fixed boom to an attachment on theextendable boom 18. The chains 25 and 26 may conveniently be so-calledfleyer-chains.

As a result of this arrangement and the described maneuvering of theextendable boom and the traveller there is obtained a doubletransmission with regard to separation of the felling head and thelimbing head in response to a given length of stroke of thepiston-cylinder device 22. This enables the boom length to be utilizedeffectively.

It will be understood that the aforedescribed and illustratedcomponents, such as the boom-projecting piston-cylinder device and thechains may be modified or replaced with other equivalent means withinthe scope of the inventive concept. For instance, the chains can bereplaced with wires.

I claim:
 1. A tree harvester for felling, limbing and cross-cutting treetrunks, comprising a limbing head and felling head assembly carried by aboom system, the limbing head and the felling head being detachablyconnectable with one another and being commonly pivotal about a point onthe boom system to a tree-felling position, wherein the boom systemincludes a fixed boom and an extendable boom structured and arranged toproject out from the fixed boom in a longitudinal direction, the limbinghead and the felling head being movable away from one another along theboom system in conjunction with a tree limbing and cross-cuttingoperation, and in different directions away from the location on theboom system at which they are commonly pivotal, the boom system beingcarried in attachment on the fixed boom at an end of the fixed boom inwhich the limbing head and felling head are commonly pivotal.
 2. A treeharvester according to claim 1, further comprising a piston-cylinderboom-projector mounted inside the extendable boom and the fixed boom,wherein the first end of said piston-cylinder is attached to theextendable boom and a second end is attached to the fixed boom.
 3. Atree harvester according to claim 1, wherein the limbing head ispivotally mounted on a transverse pivot pin at the outer end of theextendable boom.
 4. A tree harvester according to claim 2, wherein thefelling head is mounted on a traveler which is movable along the fixedboom.
 5. A tree harvester according to claim 4, wherein the traveler isconnected to the extendable boom by a chain system for movement alongthe fixed beam in a direction opposite to that in which the extendableboom is moved in relation to the fixed boom when the extendable boom isprojected out from or retracted into the fixed boom.
 6. A tree harvesteraccording to claim 4, further comprising a tilt cylinder for holding thefelling head firmly in position against the fixed boom when moving thefelling head and when cross-cutting and limbing a tree, said tiltcylinder being structured and arranged to pivot the felling head and thelimbing head to a tree felling position.
 7. A tree harvester accordingto claim 1, wherein the boom system is mounted on a tower structurecarried by a tractor-mounted crane arm via a rotator.
 8. A treeharvester according to claim 2, wherein the limbing head is pivotallymounted on a transverse pivot pin at the outer end of the extendableboom.
 9. A tree harvester according to claim 3, wherein the felling headis mounted on a traveler which is movable along the fixed boom.
 10. Atree harvester according to claim 5, further comprising a tilt cylinderfor holding the felling head firmly in position against the fixed boomwhen moving the felling head and when cross-cutting and limbing a tree,said tilt cylinder being structured and arranged to pivot the fellinghead and the limbing head to a tree felling position.